Estratégia de controle robusto para interconexão de sistemas PV trifásicos à rede elétrica

Abstract

Actually there is a great concern regarding to the replacement of non-renewable resources by renewable sources in the electricity generation. This is due to the limitation of the traditional model and the growing demand of energy. With the development of power converters and effectiveness of control schemes, renewables have been integrated in the grid, as a distributed generation models (systems). Thus, this work presents a no-standard control strategy, with the use of a robust controller for interconnecting PV (Photovoltaic) systems to the grid phase. The compensation of power quality at the common coupling point (PCC) is performed by the proposed strategy. Traditional techniques use the harmonic detection. However, in this work the control of the current is done in an indirect way without the need of this detection. In the indirect strategy the DC (Direct Current) bus voltage control must be effective for avoiding voltage fluctuations. For that reason, the bandwidth of this controller is adjusted for reducing the distorcion on network current. To achieve this, the control strategy employs a dual mode DSM-PI (Dual-Sliding Mode-Proportional Integral) that behaves as a sliding mode controller SM-PI (Sliding Mode-Proportional Integral) during the transition and like a conventional PI (Proportional Integral) in the steady-state. The output phase current are aligned with the phase angle of the utility voltage vector obtained from the use of a PLL (Phase Locked Loop). This approach allows to regulate the power flow with the harmonic compensation and also regulates the power factor at the common coupling point. For controlling of the output phase currents a double sequence regulator are used with introdution of the internal model principle. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed control system.